A traditional bowling ball contains holes into which the player generally fits a thumb and two fingers in order to propel the ball down an alley toward a set of pins. Typically, a drill and drill bit are used to bore holes of fixed diameter in the bowling balls. Difficulties can arise when a player's digits swell or contract due to various conditions, making fixed size holes more difficult or inappropriate to use under these varying conditions. Examples of such conditions are time of day, temperature, diet, or weight. Other difficulties can arise while drilling the holes that may render the bowling ball unusable or awkward to use, such as misalignment of the drill bit or drilling with a bit that is too large for the player's digit.
Previous inventions have used non-removable hole inserts. However, typically these non-removable inventions do not allow a player to change inserts without expending substantial time and effort. Other inventions have used removable inserts that can become loose during play and extend past the outer surface of the bowling ball. Still other inventions have used removable inserts which may be affixed to the bowling ball by means of a screw or other device that penetrates the bowling ball beyond the limits of the drilled hole. However, these penetrating devices may diminish the integrity of the attachment location over time such that the inserts can no longer be easily used and may require additional fastening hardware that is difficult to use. Still other inventions have used removable inserts which are held in the hole using a type of tape or glue. However, devices taped or removably glued in the hole are generally difficult to remove, may damage the insert as it is removed, and may begin to slip from their proper position in the hole as the weaker, non-permanent glue deteriorates over time. Yet other inventions have used removable spacers which are affixed to the player's digits, such as tape. However, spacers affixed to the player's digits wear out rapidly and pose a danger of remaining lodged in the hole.